Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 14: Poster II

HL 14.28: Poster

Monday, March 18, 2024, 15:00–18:00, Poster F

Nonlinear Spin to Charge Conversion and Thermopower in an inverted GaAs/AlGaAs 2DEG — •Benedikt Gruenewald, Dieter Schuh, Dominique Bougeard, Dieter Weiss, and Mariusz Ciorga — Universität Regensburg, Regensburg, Germany

Generating and detecting a nonzero spin accumulation in nonmagnetic materials by electrical means is at the heart of spintronics. A typical electrical detection scheme of injected spins involves Silsbee-Johnson spin-charge coupling, where spin accumulation at the ferromagnet-nonmagnet interface is converted into the electromotive-force, linear in the spin accumulation, measured across the junction. In nanoscale devices, an alternative solution was proposed. It was shown, that energy-dependent transmission in quantum point contacts (QPC), narrow constrictions in a two-dimensional electron gas (2DEG), leads to the voltage measured across QPC being quadratic in the spin accumulation. Here we present the results of our experiments on employing a QPC as a nonlinear detector of spin accumulation generated electrically in a 2DEG formed in the inverted GaAs/AlGaAs heterojunction. We employ a Spin Esaki Diode to electrically inject spins from the ferromagnetic semiconductor (Ga,Mn)As into the 2DEG. Both local and nonlocal measurement techniques were employed. However, separating the contribution between spin and thermopower remains a challenge.

Keywords: Spin Injection; Quantum Point Contact; Spin to Charge Conversion; Spin Esaki Diode